A domestic network is used to connect a wide range of appliances to one another. Appliances such as these may stem from the field of entertainment electronics, for example a television, video recorder, DVD player, satellite receiver, CD player, MD player, amplifier, radio, camcorder, etc.
Recently, thought has been given not only to the networking of appliances from entertainment electronics, but also appliances from other fields, for example conventional domestic appliances such as a washing machine, dishwasher, refrigerator, microwave oven, coffee machine, electric cooker, dryer, as well as domestic appliances such as heating control, a burglar alarm, or office communication appliances such as a telephone system, personal computer, fax machine etc. can in principle be integrated in a domestic network.
Industry has developed appropriate communications systems for the networking of appliances in the field of entertainment electronics. This relates primarily to the networking of appliances with the aid of the so-called IEEE 1394 bus system, which allows data to be interchanged at a very high data rate between the individual network stations. The IEEE 1394 interfaces, which are now in widespread use, generally support the specified data transmission rates of S100, S200 and S400. In this case, S100 means a data transmission rate of 100 Mbit/s. In a corresponding manner, S200 means 200 Mbit/s and S400 thus means 400 Mbit/s. High data rates such as these occur in particular with entertainment electronics appliances. This is due to the fact that the typical application for data interchange between entertainment electronics appliances is for playing back a title in the case of a video or audio source, either of video film or a piece of music, and transmitting the associated datastream to a further entertainment electronics appliance, which acts as a sink. Typical video sources are, for example, a set top box, a satellite receiver, a video recorder, a DVD player, a modem, a camcorder, a digital camera or else a personal computer. Typical audio sources are, for example, a CD player, a tuner/radio, a DVD player, a cassette player (DAT/DCC), an MD player, an MP3 player, a personal computer, etc.
Sinks for a video datastream may, in particular, be: a computer monitor, a television, etc. The appliances with a video display unit are pure sinks for video data. The following items may, however, also be regarded as sinks for video data: all recording appliances such as video recorders, which use various recording media. For example, this includes classical video recorders based on VHS or S-VHS Standard, digital video recorders based on the D-VHS Standard, digital video recorders based on DVD, in particular DVD-R, DVD+RW, DVD-RW and DVD-RAM technology and hard disk recorders which are being increasingly used in digital set top boxes.
Sinks for audio data include, for example, an amplifier or digital loudspeakers, which effectively act as active boxes and each contain their own amplifier. As in the case of sinks for video data, combination appliances also exist, however, which act as source and sinks for audio data, such as CD recorders, audio tape recorders, cassette players (DAT/DCC), MP3 players, MD players, personal computers, video recorders, DVD recorders, etc.
However, only the lower layers of the ISO/OSI reference model for data communication are specified in the IEEE Standard 1394. These are the physical layer, the data link layer and parts of the network layer as well as the transport layer. The higher layers of the ISO/OSI reference model are not specified in this Standard.
A consortium of companies has taken over the task of specifying the higher layers. The corresponding system proposal/standard has become known by the expression HAVi (Home Audio Video interoperability). The HAVi Standard has primarily been worked out for communication between entertainment electronics appliances in the domestic network field. It is thus possible to operate/to control the appliances in the network from a central appliance which is specially equipped for this purpose. The central appliance is generally equipped with a video display unit. This may therefore be, in particular, a television or a personal computer. The HAVi technology allows the network structure to be displayed on a display, allows one of the network appliances to be selected, allows a user interface to be produced for the selected appliance, and then allows this appliance to be operated/controlled.